By making your own pistons you can make metering syringes of any size.

I have toyed with making a dual syringe for metering air and fuel together much like an epoxy syringe. Either a pair of pipes with the proper ratio in cross section is needed or a lever to push the plungers in the proper ratio would be needed to dispense a purge fuel air cycle into a launcher. It would be for rapid reloads.

In medical supplies, they are not IV syringes. They are feeding tube syringes. The tip is larger than an IV syringe so a needle won't fit on it.